using System;

public class Program

{

    public class Node

    {

        public int Value { get; set; }

        public Node Left { get; set; }

        public Node Right { get; set; }

    }

    public static bool pathSumUp(Node node, int x) {

        if (node == null) {

            return false;

        }

        if (node.Value == x) {

            return true;

        }

        int y = x - node.Value; // image x is HUUUGE

        // sum up on the left or right

        return pathSumUp(node.Left, y) || pathSumUp(node.Right, y);

    }

    public static void Main()

    {

        /*

        Binary Search Tree:

          3

         / \

        1   5

        */

        var tree = new Node {

            Value = 3,

            Left = new Node { Value = 1 },

            Right = new Node { Value = 5 }

        };

        Console.WriteLine(pathSumUp(tree, 4));

        Console.WriteLine(pathSumUp(tree, 8));

        Console.WriteLine(pathSumUp(tree, 11));

        Console.WriteLine(pathSumUp(tree, 3));  

    }

}